The present invention generally relates to mining and construction tools, and more particularly relates to cutting bits with hard cutting tip centering and braze joint control features.
Cutting bits are used in various road milling, mining and excavating operations. The cutting bits are mounted on a support structure such as a rotary drum. Each cutting bit typically has a hard, wear resistant cutting tip made of a material such as tungsten carbide that is attached to a generally conical steel head portion of the cutting bit.
The hard cutting tip is typically brazed into a notch or pocket formed in the head portion of the cutting bit using a braze alloy so that a braze joint is formed between the hard cutting tip and the cutting bit body, i.e. the head portion. Throughout the course of the cutting operation, the braze joint experiences severe stresses due to the continual intermittent violent impingement of the cutting bit against the particular substrate material. Over the course of time, the braze joint can experience sufficient stress so as to fail thereby allowing the hard cutting tip to separate from the cutting bit body. Obviously, if the cutting bit loses the hard cutting tip, the cutting bit is no longer useful for the cutting operation.
It is, therefore, important that the braze joint provide a uniform and consistent attachment between the hard cutting tip and the cutting bit body, as well as, provide a strong and reliable connection therebetween so as to prevent the hard cutting tip from separating from the cutting bit body.
Thus, it can be appreciated that it would be highly desirable to provide an improved cutting bit that overcomes disadvantages, shortcomings and limitations of known tools. It can also be appreciated that it would be highly desirable to provide an improved cutting bit with an improved braze joint that overcomes disadvantages, shortcomings and limitations of known tools.